Superoxide anion, O2-, is involved in a variety of biological processes and has most recently been implicated as the active agent responsible for rheumatoid arthritis. Numerous pathways have been proposed to explain the participation of O2- in these processes. However, there is, in fact, little that is actually known about the basic reactivity of O2- and in particular about its reactivity with possible biological substrates. We are proposing to study the basic reactions of both uncoordinated and transition metal-coordinated superoxide, chosen to reflect its potential reactivity with possible biological substrates. Solutions of potassium superoxide in "crown ether" - containing solvents will be used to study the reaction of O2- under both protic and aprotic conditions. The reactions of superoxide with various substrates (e.g. olefins, aromatic and aliphatic hydrocarbons, peroxides, hydroperxides, etc.), whose oxidation or reduction may involve superoxide or superoxide-derived agents. Preliminary results suggest the reactivity of O2- is different in several respects from that previously supposed. The information gained from such studies will aid in understanding the role of O2- in biological systems and possibly lead to a means of combating its deleterious effects and enhancing its potentially therapeutic properties.